System, method, and computer-readable medium for concurrent termination of multiple calls at a mobile terminal

ABSTRACT

A system, method and computer-readable medium for allocating multiple subscriptions to a single mobile terminal thereby allowing concurrent termination of multiple calls at the mobile terminal are provided. A mobile terminal adapted to terminate multiple concurrent calls is described. In one implementation, a network need not have any configuration data regarding the multi-line capabilities of the mobile terminal. In other implementations, network-centric mechanisms are provided for allowing multiple concurrent calls to be terminated by a mobile terminal. Multiple concurrent calls may be terminated at a mobile terminal on separate carrier frequencies or alternatively may be terminated on a common carrier frequency.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority of and is a continuation of U.S. Ser.No. 11/752,042, entitled SYSTEM, METHOD, AND COMPUTER-READABLE MEDIUMFOR CONCURRENT TERMINATION OF MULTIPLE CALLS AT A MOBILE TERMINAL, filedon May 22, 2007, now issued U.S. Pat. No. 9,002,364, issued on Apr. 7,2015, incorporated herein by reference in its entirety.

FIELD OF THE INVENTION

The present disclosure relates to telecommunications and, moreparticularly, to mechanisms for terminating calls with mobile terminals.

BACKGROUND

Corporations are increasingly relying on the use of cellular technologyby their employees. In many instances, an enterprise may assign acellular telephone to an employee and maintain a subscription of thecellular telephone. The enterprise subscription may be tailored toauthorized employee usage, e.g., allow or disallow calls at certaintimes of the day, restrictions of supplementary services or longdistance calls, etc.

Because of the popularity of cellular services, many employees typicallyhave a personal cellular telephone. Thus, an enterprise employee thathas been assigned a corporate cellular telephone may carry multiplecellular telephones which is often considered a nuisance. Often, anemployee may prefer the personal handset rather than an employeeassigned mobile terminal. However, corporate mobile accounts aretypically purchased through a single carrier and thus no contemporarymechanism provides for porting or otherwise using the employee'spersonal account on the corporate assigned mobile terminal or viceversa. Even if the corporate account and an employee's personal accountare managed by a common carrier, no mechanism exists for managing twoaccounts on a common terminal. Thus, the employee is required to carrythe corporate assigned mobile terminal for work-related services and theuser's personal mobile terminal for personal communications.

SUMMARY OF THE INVENTION

Embodiments disclosed herein provide mechanisms for allocating multiplesubscriptions to a single mobile terminal. Additionally, a mobileterminal adapted to terminate multiple concurrent calls is described. Inone implementation, a network need not have any configuration dataregarding the multi-line capabilities of the mobile terminal. In otherimplementations, network-centric mechanisms are provided for allowingmultiple concurrent calls to be terminated by a mobile terminal.Multiple concurrent calls may be terminated at a mobile terminal onseparate carrier frequencies or alternatively may be terminated on acommon carrier frequency.

BRIEF DESCRIPTION OF THE DRAWINGS

Aspects of the present disclosure are best understood from the followingdetailed description when read with the accompanying figures, in which:

FIG. 1 is a diagrammatic representation of a network in whichembodiments disclosed herein may be implemented;

FIG. 2 is a diagrammatic representation of an exemplary HLR record thatdefines a subscriber profile implemented in accordance with anembodiment;

FIG. 3 is a simplified block diagram of an exemplary mobile terminal inwhich embodiments may be implemented;

FIG. 4 is a diagrammatic representation of an exemplary softwareconfiguration of a mobile terminal adapted for concurrent multi-calltermination in accordance with an embodiment;

FIG. 5A is a diagrammatic representation of an exemplary cellularnetwork primary band that may be used for allocating multiple concurrentcalls in accordance with an embodiment;

FIG. 5B is a diagrammatic representation of a time division multiplexaccess (TDMA) frame of a carrier frequency that may facilitateconcurrent call termination with a mobile terminal in accordance with anembodiment;

FIG. 6A is a diagrammatic representation of a cell configuration of anetwork system in which embodiments described herein may be implemented;

FIG. 6B depicts a diagrammatic representation of overlapping cells thatmay conjunctively facilitate concurrent termination of multiple calls toa mobile terminal in accordance with an embodiment;

FIG. 7 is a flowchart depicting processing of frequency allocation for acall setup to a multi-line mobile terminal in accordance with anembodiment;

FIG. 8 is a flowchart that depicts processing of a multi-line secondcall set-up subroutine implemented in accordance with an embodiment;

FIG. 9 is a flowchart depicting processing of a multi-line mobileterminal call set-up routine implemented in accordance with anembodiment;

FIGS. 10A-10C depict a flowchart of processing of a multi-line secondcall set-up subroutine and corresponding diagrammatic representations ofcarrier frequency configurations implemented in accordance with anembodiment;

FIGS. 11A-11D depict a flowchart of processing of a secondary intra-cellhandover procedure that facilitates concurrent termination of multiplecalls with a mobile terminal and corresponding representations ofcarrier frequency configurations in accordance with an embodiment;

FIG. 12 is a flowchart depicting a call set-up processing routineproviding preference to carrier frequencies that do not have amulti-line mobile terminal call allocated thereon for call requestsimplemented in accordance with an embodiment;

FIG. 13 is a flowchart depicting a call termination applicationprocessing for providing mid-call services in accordance with anembodiment; and

FIG. 14 is a flowchart depicting a call transfer procedure executed at amulti-line mobile terminal in accordance with an embodiment.

DETAILED DESCRIPTION

It is to be understood that the following disclosure provides manydifferent embodiments, or examples, for implementing different featuresof various embodiments. Specific examples of components and arrangementsare described below to simplify the present disclosure. These are, ofcourse, merely examples and are not intended to be limiting. Inaddition, the present disclosure may repeat reference numerals and/orletters in the various examples. This repetition is for the purpose ofsimplicity and clarity and does not in itself dictate a relationshipbetween the various embodiments and/or configurations discussed.

FIG. 1 is a diagrammatic representation of a network 100 in whichembodiments disclosed herein may be implemented. Network 100 may includea cellular network system 110, such as a Global System for Mobile (GSM)Communications network, a code division multiple access (CDMA) network,a mobile network utilizing IMT-2000, or another suitable mobile network.Cellular network system 110 generally includes a Switching System (SS)120 and a Base Station System (BSS) 130. In the examples providedherein, mobile network architecture components are made with referenceto the GSM, the most popular standard for mobile phones in the world.GSM is both an air interface and networking protocol. The most popularalternative combines the Code Division Multiple Access (CDMA) airinterface protocol and the ANSI-41 networking protocol.

Each of SS 120 and BSS 130 contain a number of functional units wellunderstood by those skilled in the art, and a detailed explanation ofthe various components is unnecessary. Nevertheless, a cursory review ofvarious components is provided. SS 120 contains a Mobile servicesSwitching Center (MSC) 122, a Home Location Register (HLR) 124, and aVisitor Location Register (VLR) 126. MSCs carry out switching functionsand manage the communications between mobile phones and the PublicSwitched Telephone Network (PSTN) 190. HLR 124 comprises the centraldatabase that contains details of each mobile phone subscriber that isauthorized to use the cellular core network. VLR 126 comprises adatabase which stores information about all the mobile terminals thatare currently serviced by the associated MSC (MSC 122 in the presentexample). VLR 126 stores various information regarding the mobileterminals, such as the current location area identity that specifies aparticular base station controller (BSC) that the mobile station iscurrently serviced by.

Various other sub-systems or functional modules may, and typically are,included in SS 120, such as an Authentication Center, an EquipmentIdentity Register, or various other functions. A serving general packetradio service (GPRS) support node (SGSN) 128 may be included in cellularnetwork system 110 to facilitate provisioning of packet services to andfrom mobile terminals in network system 110. GPRS provides mobilitymanagement, session management and transport for Internet Protocolpacket services in GSM cellular packet networks.

Network system 110 may also include a signaling system, such as an SS7network 160. SS7 network 160 provides a set of telephony signalingprotocols which are used to set up the vast majority of the world's PSTNtelephone calls. SS7 network 160 is also used in cellular networks, suchas GSM and UMTS, for circuit switched voice and packet-switched dataapplications. As is understood, SS7 network 160 includes varioussignaling nodes, such as any number of service control points (SCPs)162, signal transfer points (STPs) 164, and service switching points(SSPs) 166.

BSS 130 contains a Base Station Controller (BSC) 132 that may be incommunication with and in control of a plurality of Base TransceiverStations (BTSs) 134-138. Each individual BTS 134-138 under the controlof a given BSC 132 may define a radio cell operating on a set of radiochannels thereby providing service to a Mobile Terminal (MT) 140.Cellular network system 111 may be implemented in a similar manner ascellular network system 110 or may employ another cellular networkarchitecture. Cellular network system 110, as well as other cellularnetworks such as cellular network 111, may interface with PSTN 190.

FIG. 2 is a diagrammatic representation of an exemplary HLR record 200that defines a subscriber profile implemented in accordance with anembodiment. In general, HLR 124 may, and typically does, includethousands of records each associated with a particular mobilesubscriber. Each HLR record includes details of a respective subscriberauthorized to use cellular network 110. In the illustrative example, HLRrecord 200 is representative of an HLR record allocated for mobileterminal 140.

HLR record 200 comprises a plurality of fields 202-220 which each storeinformation regarding a particular mobile terminal assigned to asubscriber of cellular network 110. Fields 402-420 have respectivelabels of “IMSI”, “MSISDN”, “Voice”, “SMS.”, “GPRS_Settings”, “VLR_ID”,“SGSN_ID”, “SMS-CSI”, “SMSC_Number,” and “MSC_ID”. A particular field,e.g., IMSI field 402 and MSISDN field 404, may be designated as a keyfield and each respective data element is unique within key fields402-404.

In the illustrative example, IMSI field 402 maintains an InternationalMobile Subscriber Identity (IMSI) stored in the subscriber identitymodule (SIM) of the mobile terminal for which HLR record 200 isallocated. The IMSI comprises a unique number associated with aparticular mobile terminal. The IMSI is typically a 15-digit numberhaving the first 3 digits that specify a mobile country code followed bya 3-digit mobile network code associated with cellular network 110 towhich the mobile terminal is registered. The remaining digits maycomprise a mobile subscriber identification number (MSIN) assigned tothe customer associated with the mobile terminal. In the illustrativeexample, the IMSI has a value of “3101501234567190” assigned thereto.

A mobile subscriber ISDN (MSISDN) field 204 may store the MSISDN, ordirectory number, assigned to the mobile terminal for which record 200is allocated. In the illustrative example, MSISDN field 204 specifies aMSISDN number of “19124441001”, that is the directory number assigned tomobile terminal 140. Each of IMSI field 202 and MSISDN field 204 may beused as primary keys for accessing HLR record 200.

HLR record 200 may record various subscription services for the mobileterminal. In the illustrative example, various service fields may havevalues that indicate whether the subscriber for which the HLR record isallocated is authorized to use a particular service. In the presentexample, Voice field 206 has a value of true (T) that indicates thatassociated subscriber is authorized for voice service, and SMS field 208has a value of true that indicates the mobile terminal is authorized tooriginate and receive SMS messages. Various other service fields may,and typically are, included in HLR 400 that each specify any one or moreof various subscription services, such as call waiting, call forwarding,and the like.

A GPRS_Settings field 210 may specify whether the mobile terminal has aGPRS subscription and settings thereof. For instance, GPRS_Settingsfield 210 may have a false setting or have another indicator thatspecifies the mobile terminal associated with HLR record 200 does nothave a valid GPRS subscription. In the event that the mobile terminalhas a GPRS subscription, GPRS_Settings field 210 may specify a serviceclass. In the illustrative example, GPRS_Settings field 210 specifiesthat the associated mobile terminal has a GPRS subscription with aservice setting of “Class_(—)10”.

VLR_ID field 212 may specify the current VLR servicing the mobileterminal associated with HLR record 400. In the present example, VLR_IDfield 212 indicates the mobile terminal is being serviced by a VLRhaving a VLR ID of VLR₁. In a similar manner, SGSN_ID field 214 mayspecify the current SGSN servicing the mobile terminal associated withHLR record 200. In the present example, SGSN_ID field 214 indicates themobile terminal is being serviced by an SGSN having an ID of SGSN₁.

HLR record 200 may include a Short Message Service-CustomizedApplications for Mobile networks Enhanced Logic (CAMEL) SubscriptionInformation (SMS-CSI) field 216 containing trigger information. In theillustrative example, the trigger information maintained in SMS-CSIfield 216 is diagrammatically represented as “trigger_info”. A shortmessage service center (SMSC) Number field 218 may include anidentifier, e.g., an SS7 point code, assigned to an SMSC that is toservice the associated subscriber. In the illustrative example,SMSC_Number field 218 has a value of Point Code_(c). An MSC_ID field 220may include an identifier, e.g., a point code, of the MSC currently, ormost recently, servicing the mobile terminal associated with HLR record200. In the present example, the point code of the MSC specified byMSC_ID field is represented as “Point Code_(x)”.

In accordance with an embodiment, mechanisms are provided for allocatingmultiple subscriptions to a single mobile terminal. Additionally, amobile terminal adapted to terminate multiple concurrent calls isdescribed in accordance with an embodiment. In one implementation, anetwork need not have any configuration data regarding the multi-linecapabilities of the mobile terminal. In other implementations,network-centric mechanisms are provided for allowing multiple concurrentcalls to be terminated by a mobile terminal.

FIG. 3 is a simplified block diagram of an exemplary mobile terminal 140in which embodiments may be implemented. Mobile terminal 140 includes anantenna 302 that may be coupled with an RF switch 304, e.g., a duplexer,coupled with an RF transceiver 306. Transceiver 306 may be coupled withan analog baseband 308 that may handle a variety of analog signalprocessing functions. In the present example, analog baseband 308 isinterconnected with a microphone 310, a keypad 312, a vibrator 314 orother ring alert mechanism, a headset speaker 316, and a loudspeaker 330for output of speakerphone and incoming call alert audio. Analogbaseband 308 may include or interface with an analog to digitalconverter for converting analog input supplied to microphone 310 into adigital format that may be supplied to a digital baseband 318. Digitalbaseband 318 may interface with various digital components of mobileterminal 140, such as a memory 320, an optional subscriber identitymodule (SIM) card 322, and a liquid crystal display controller 326 thatdrives a display 328. Memory 320 may be implemented as a flash memory, arandom access memory, an electronically erasable programmable read-onlymemory, another solid state device, or a combination thereof. Digitalbaseband 318 may additionally include or interface with one or moreencoders, digital to analog converters, or other modules. A power supply332 may be coupled with various system modules as is understood.

In accordance with an embodiment, optional SIM card 322 may include twoSIMs 340 and 341 each associated with a subscription, or alternatively aDual SIM or Multi-SIM card in which two or more subscriptions aresupported via a single SIM. Thus, mobile terminal 140 may have two HLRrecords similar to HLR record 200 allocated therefore, and each HLRrecord specifies a separate subscription associated with mobile terminal140. The HLR records may be maintained by a common carrier, e.g., theoperator of network system 110 depicted in FIG. 1. Alternatively, afirst HLR record may be maintained by one carrier such as the operatorof cellular network system 110, and another HLR record may be maintainedby another carrier, such as an operator of cellular network system 111,thereby allowing separate subscriptions to be provided to mobileterminal 140 from separate carriers.

In accordance with another embodiment, mobile terminal 140 mayoptionally include a second antenna 303 and RF transceiver 307 coupledwith an RF switch 305. In this implementation, a first call may becarried over antenna 302 and transceiver 306, and a second call mayconcurrently be carried over antenna 303 and transceiver 307. In otherembodiments, antenna 303, switch 305, and transceiver 307 may beexcluded from mobile terminal 140, and multiple calls may concurrentlybe carried over antenna 302 and transceiver 306 as described more fullyhereinbelow.

FIG. 4 is a diagrammatic representation of an exemplary softwareconfiguration 400 of mobile terminal 140 adapted for concurrentmulti-call termination in accordance with an embodiment. In theexemplary configuration of FIG. 4, the mobile terminal is configuredwith access network-specific software entities 460, e.g., protocol anddriver software associated with a particular access network technology,such as GSM, UMTS, CDMA or another suitable radio access network, and isdependent on the particular cellular network in which the mobileterminal is to be deployed. While configuration 400 depicts a mobileterminal adapted for deployment in a single access network technologytype, the mobile terminal may be implemented as a multi-mode device andmay accordingly include a plurality of access-specific entities inaccordance with an embodiment. The particular configuration 400 isillustrative only and is provided only to facilitate an understanding ofembodiments disclosed herein.

In the illustrative example, configuration 400 includes a cellular modemdriver 402 for providing a physical interface with the access network inwhich the mobile terminal is deployed. An access-stratum 404 and anon-access stratum 406 may be included in configuration 400. A cellularradio interface 408 may be communicatively coupled with lower layers ofconfiguration 400 and may additionally interface with network andsession management layers, e.g., a network stack 410 such as a TCP/IPlayer.

Configuration 400 may optionally include a call termination application412 for providing mobile terminated mid-call services, such as callwaiting, call forwarding, conference calling, and the like, as describedmore fully hereinbelow. Additionally, configuration 400 includes anoperating system 414, such as Symbian, Blackberry O/S, or anotheroperating system suitable for mobile applications, and may coordinateand provide control of various components within the mobile terminal.

FIG. 5A is a diagrammatic representation of an exemplary cellularnetwork primary band 500 that may be used for allocating multipleconcurrent calls in accordance with an embodiment. In the illustrativeexample, primary band 500 includes two 25 MHz sub-bands—an uplink band510 and a downlink band 520. A given operator may be allocated a portionof primary band 500 for provisioning of cellular service. In theillustrative example, uplink band 510 comprises an 890-915 MHz sub-band,and downlink band 520 comprises a 935-960 MHz sub-band —spectrumtypically allocated for a GSM network. Other primary bands may beallocated for use in a GSM system, e.g., an 1800 MHz band comprising anuplink band of 1710-1785 MHz and a downlink band of 1805-1880 MHz.

In GSM, each of the uplink band 510 and downlink band 520 are subdividedinto 124 200 KHz carrier frequencies that are each time divisionmultiplexed (TDM) allowing for eight full-rate or sixteen half-ratespeech channels per carrier frequency. Allocation of a traffic channelto a mobile terminal comprises assignment of the mobile terminal to arespective time slot of both an uplink carrier frequency and a downlinkcarrier frequency. As referred to herein, a channel comprises an uplinkcarrier frequency and a downlink carrier frequency, and a trafficchannel refers to both an uplink carrier frequency slot and a downlinkcarrier frequency slot. Additionally as referred to herein, allocationof a time slot implies allocation of both a time slot on an uplink anddownlink carrier frequency.

FIG. 5B depicts a diagrammatic representation of a time divisionmultiplex access (TDMA) frame 530 of a carrier frequency that mayfacilitate concurrent call termination with a mobile terminal inaccordance with an embodiment. Frame 530 comprises multiplexed timeslots 530 a-530 h (illustratively designated TS0-TS7) transmitted onrespective bursts as is understood. Uplink and downlink frames aresimilarly multiplexed. When a channel is allocated to a mobile terminal,a particular slot of the available slots of frame 530 is allocated tothe mobile terminal, and transmissions to (or from) the mobile terminalare made on the allocated slot of a sequence of TDM frames. Inaccordance with an embodiment, multiple calls may be terminated to amulti-line mobile terminal by assignment of multiple slots of a TDMframe similar to frame 500 as described more fully hereinbelow.

Typically a carrier is only allocated a portion of band 500, or anothersuitable band, because many carriers may be licensed to the availablespectrum. As is known, a carrier typically partitions the spectrumlicensed thereto such that a subset of frequencies are used in aparticular cell, with other frequency subsets used in adjacent cells ina manner that provides for so-called frequency reuse. Frequencies may bereused in the network a few cells away from another cell using the samefrequency at a distance that interference created by the use of the samespectrum is at an acceptable level.

FIG. 6A is a diagrammatic representation of a cell configuration 600 ofa network system in which embodiments described herein may beimplemented. Cell configuration 600 comprises cells 602-612 operated bya carrier (designated Carrier 1) that each provide radio coverage for ageographic area. Cells 602-612 may be provisioned in cellular networksystem 110 depicted in FIG. 1. Each cell 602-612 includes a BTS (notshown) which is allocated a particular frequency subset of the spectrumlicensed to the carrier. In the illustrative example, cells 602-610 areallocated respective frequency sets fset₁-fset₅. Cell 612 may be locatedat sufficient distance from cell 602 such that both cell 602 and cell612 are allocated a common frequency set, or a portion thereof. Acarrier typically manages thousands of cell sites, and the exampledepicted in FIG. 6A is greatly simplified to facilitate an understandingof disclosed embodiments.

Another carrier (designated Carrier 2) may provision cells 620-630.Cells 620-630 may be provisioned in cellular network system 111 depictedin FIG. 1. Assuming that Carrier 1 and Carrier 2 may service a commongeographic region, the frequency sets fset₆-fset₁₁ licensed to Carrier 2for allocation of cells 620-630 comprise different sets of frequenciesthan the frequency sets fset₁-fset₅ licensed to Carrier 1.

The depiction of cells 602-612 and cells 620-630 in FIG. 6A is notintended to imply geographic distinction between the coverage areas.Rather, one or more cells 602-612 that provide service to subscribers ofnetwork system 110 may geographically overlap, at least partially, withone or more cells 620-630 that provide service to subscribers of networksystem 111. For example, FIG. 6B depicts a diagrammatic representationof cell 612 of network system 110 that overlaps with cell 620 of networksystem 111 in a manner that facilitates multiple call termination with amobile terminal in accordance with an embodiment. In the illustrativeexample, cell 612 is provisioned by a BTS 134 of carrier network 110,and cell 622 is provisioned by a BTS 135 of cellular network system 111.In accordance with an embodiment, multiple subscriptions may be assignedto a mobile terminal 140. In a first implementation, assume mobileterminal 140 has a respective subscription in cellular network system110 and cellular network system 111. When mobile terminal 140 isimplemented with dual SIM card 322, or alternatively separate butmultiple SIM cards, and multiple antenna 302-303 and correspondingtransceivers 306-307, mobile terminal 140 may have two concurrent callsterminated therewith via respective RF links with BTSs 134 and 135 ofnetwork systems 110 and 111. From a network perspective, neither networksystem 110 nor network system 111 requires any awareness of themultiple-call capabilities of mobile terminal 140 because each networkhas a subscription allocated to a respective SIM 340-341. For example,each of network systems 110 and 111 may maintain a respective HLR recordsimilar to that depicted in FIG. 2 that includes a respective identifierassigned to mobile terminal 140. The HLR record maintained by cellularnetwork system 110 may maintain an IMSI of SIM 340, and another HLRrecord maintained by cellular network system 111 may maintain anotherIMSI of SIM 341. Accordingly, a call may be set up and terminated withmobile terminal 140 by a first cellular network that recognizes mobileterminal 140 based on an IMSI or other unique identifier stored in SIM340, and another call may be set up and terminated with mobile terminal140 by a second cellular network that recognizes mobile terminal 140based on another IMSI or unique identifier stored in SIM 341. A call maybe set up and terminated with mobile terminal 140 by one network withwhich mobile terminal 140 has a subscription while another call isin-progress or concurrently being set up by another cellular networkwith which mobile terminal 140 has a separate subscription. In otherimplementations, mobile terminal 140 may not be provisioned with a SIMcard but may be equipped with multiple antennas and transceivers. Inthis instance, multiple carrier networks may maintain respectivesubscriptions for mobile terminal 140, e.g., based on an electronicserial number or other identifier of the mobile terminal. Accordingly,mobile terminal 140 may be provided with multiple concurrent callterminations in a manner similar to that described above with regard toFIG. 6B.

In accordance with another embodiment, concurrent calls to multi-linemobile terminal 140 may be provisioned by a common cellular networksystem. In accordance with an embodiment, multiple subscriptions may bemaintained for multi-line mobile terminal 140 by a common carrier. Forexample, if mobile terminal 140 is equipped with multiple SIMs or a dualSIM card 322, a subscription may be associated with each SIM. Otheridentifiers may be substituted for SIMs 340 and 341 for mobile terminalsthat do not employ SIMs. In accordance with another embodiment, a singlesubscription that features a multi-line subscription service may beprovisioned to a mobile terminal. In this instance, terminal 140 mayfeature a single SIM, and the subscription may include an identifier,e.g., in the HLR record allocated for mobile terminal 140, thatindicates multi-line authorization for the mobile terminal.

In the event that mobile terminal 140 is equipped with two antennas302-303 and corresponding transceivers 306-307, multiple calls may beconcurrently terminated with mobile terminal 140 on separate carrierfrequencies provided by a single network system. In this implementation,the network may be configured to facilitate provisioning of separatecarrier frequencies to mobile terminal 140 in a manner that reduces thelikelihood of interference between the two carrier frequencies.

FIG. 7 is a flowchart 700 depicting processing of frequency allocationfor a call setup to multi-line mobile terminal 140 in accordance with anembodiment. The processing steps of FIG. 7 may be implemented ascomputer-executable instructions executable by a processing system, suchas a processing system of one or more of a mobile switching center orbase station subsystem. The call set-up routine is invoked (step 702),and a call set-up request for a mobile terminal is received (step 704).An evaluation may be made to determine if either the originating ordestination device comprises a multi-line mobile terminal (step 706). Inneither the originating nor destination device comprises a multi-linemobile terminal, the call may be conventionally set-up (step 708), andthe call set-up routine cycle may end (step 722).

Returning again to step 706, in the event that either the origination ordestination device comprises a multi-line mobile terminal, an evaluationmay be made to determine if the multi-line mobile terminal is presentlyengaged in a call (step 710). In the event the multi-line mobileterminal is engaged in a call, processing may proceed to a multi-linesecond call set-up subroutine (step 712) described more fullyhereinbelow with reference to FIG. 8.

Returning again to step 710, in the event that the multi-line mobileterminal is not presently engaged in a call, the available frequenciesfor voice calls may be evaluated to identify a frequency, f₁, with agreatest potential frequency separation or spacing from other availablefrequencies (step 714), e.g., a frequency at or near an upper or lowerband limit available for channel allocation. A time slot of theidentified frequency, f₁, may then be allocated for the current callrequest (step 716), and the call may be set up on the identifiedfrequency (step 718). It is understood that identification of a carrierfrequency f₁ includes identification of a particular channel comprisingan uplink frequency and a downlink frequency. The multi-line mobileterminal may be marked as able to receive a second call (step 720). Forexample, a flag or other designator may be set to indicate a second callmay be set up with the mobile terminal. The flag may, for example, bemaintained in the mobile terminal's HLR record, within the base stationcontroller, within the base station, or another suitable network node.The call setup routine cycle may then end according to step 722.

FIG. 8 is a flowchart 800 that depicts processing of a multi-line secondcall set-up subroutine implemented in accordance with an embodiment. Theprocessing steps of FIG. 8 may be implemented as computer-executableinstructions executable by a processing system, such as a processingsystem of one or more of a mobile switching center or base stationsubsystem. The processing steps of FIG. 8 generally correspond to step712 depicted in FIG. 7.

The set-up subroutine is invoked (step 802), e.g., on receipt of a callrequest to a multi-line mobile terminal and after a determination ismade that the multi-line mobile terminal is currently engaged in a call.An available frequency having the greatest spacing from the frequency,f₁, with which the current in-progress call is carried is thenidentified (step 804). The identified frequency may then be evaluated todetermine if it is a harmonic of the in-call frequency, f₁ (step 806).In the event that the identified frequency is determined to be aharmonic of the current in-progress call frequency, f₁, the identifiedfrequency may be marked as excluded from the current frequency search toavoid unacceptable RF interference between the RF links of the calls(step 808), and processing may return to step 804 to search for anotherfrequency having the greatest separation from the current in-progresscall frequency.

When a determination is made that an identified frequency is not aharmonic of the current in-progress call frequency, a time slot on theidentified frequency may be allocated for the second call (step 810),and the second call may then be allocated on the allocated time slot(step 812). The call setup subroutine cycle may then end (step 814).

In accordance with another embodiment, multiple concurrent calls may beterminated at a mobile terminal using a single carrier frequency forboth calls. Advantageously, mobile terminal 140 need only be equippedwith a single antenna and transceiver. Furthermore, by allocatingmultiple calls on a single frequency, RF interference that may occurwhen terminating multiple calls on multiple carrier frequencies isavoided.

FIG. 9 is a flowchart 900 depicting processing of a multi-line mobileterminal call set-up routine for terminating multiple calls on a commoncarrier frequency in accordance with an embodiment. The processing stepsof FIG. 9 may be implemented as computer-executable instructionsexecutable by a processing system, such as a processing system of one ormore of a mobile switching center or base station subsystem. The callset-up routine is invoked (step 902), and a call set-up request for amobile terminal is received (step 904). An evaluation may be made todetermine if either the originating or destination device comprises amulti-line mobile terminal (step 906). If neither the originating nordestination device comprises a multi-line mobile terminal, the call maybe conventionally set-up (step 908), and the call set-up routine cyclemay end (step 922).

Returning again to step 906, in the event that either the origination ordestination device comprises a multi-line mobile terminal, an evaluationmay be made to determine if the multi-line mobile terminal is presentlyengaged in a call (step 910). In the event the multi-line mobileterminal is engaged in a call, processing may proceed to a multi-linesecond call set-up subroutine (step 912) described more fullyhereinbelow with reference to FIG. 10A.

Returning again to step 910, in the event that the multi-line mobileterminal is not presently engaged in a call, the available frequenciesfor voice calls may be evaluated to identify a frequency, f₁, with agreatest number of available time slots (step 914). For example, thefrequency set of the current cell serving mobile terminal 140 may beevaluated to determine if any carrier frequencies are wholly unoccupied,that is have no current calls and thus have the complete eight timeslots available. If no carrier frequencies of the cell frequency sethave eight time slots available, an evaluation may be made to determineif any frequencies have seven available slots. The general procedure maybe repeated until a carrier frequency is identified that has anavailable time slot. A time slot of the identified frequency, f₁, maythen be allocated for the current call request (step 916), and the callmay be set up on the identified frequency, f₁ (step 918). The multi-linemobile terminal may be marked as able to receive a second call (step920). For example, a flag or other designator may be set to indicate asecond call may be set up with the mobile terminal. The flag may, forexample, be maintained in the mobile terminal's HLR record, within thebase station controller, within the base station, or another suitablenetwork node. The call setup routine cycle may then end according tostep 922.

FIG. 10A is a flowchart 912 that depicts processing of a multi-linesecond call set-up subroutine implemented in accordance with anembodiment. The processing steps of FIG. 10A may be implemented ascomputer-executable instructions executable by a processing system, suchas a processing system of one or more of a mobile switching center orbase station subsystem. The processing steps of FIG. 10A generallycorrespond to step 912 depicted in FIG. 9.

The set-up subroutine is invoked (step 1002), e.g., on receipt of a callrequest to a multi-line mobile terminal and after a determination ismade that the multi-line mobile terminal is currently engaged in a call.An evaluation may be made to determine if a time slot is available onthe frequency, f₁, on which the mobile terminal is currently engaged ina call (step 1004). In the event that a time slot is available on thefrequency, f₁, of the current call, an available time slot of thefrequency f₁ may be allocated for the incoming call (step 1006), and theincoming call may be set-up on the allocated time slot (step 1008). Theset-up subroutine cycle may then end (step 1024).

Returning again to step 1004, in the event that no time slots areavailable on the frequency, f₁, on which the current call is maintained,an evaluation may be made to determine if any other frequency, f₂, isavailable in the cell in which the mobile terminal is being servicedthat has a plurality of time slots available (step 1010). In the eventthat no frequency, f₂, is identified with a plurality of available timeslots, an evaluation may be optionally performed to determine if anyother frequency, f₂, is available in the cell servicing the mobileterminal that has a single time slot available (step 1012). In the eventthat no frequency is identified that has an available time slot, a busytermination may be invoked to the calling party (step 1014). Forexample, the calling party may be terminated with a voice mail server,an SMS service, or other suitable busy call termination service.Returning again to step 1012, if a frequency is identified that has anavailable time slot, a secondary intra-cell handover procedure may beinvoked to free a time slot on the carrier frequency, f₁, of thein-progress call (step 1016) to facilitate concurrent call terminationwith the mobile terminal as described more fully hereinbelow withreference to FIG. 11A.

Returning again to step 1010, in the event that a frequency, f₂, isidentified that has a plurality of time slots available, an intra-cellhandover may be invoked for the in-progress call from frequency f₁ tofrequency f₂ (step 1018). As is understood, an intra-cell handovercomprises a procedure in which a call (or data session) is transferredfrom one channel to another within a common cell. That is, a call thatis subjected to an intra-cell handover is transferred from a firstfrequency of a frequency set of the cell to a second frequency of thecell's frequency set. Thus, in the event that a second call request isdirected to a multi-line mobile terminal that is occupying a time slotsof a carrier frequency, f₁, with no available time slots, an intra-cellhandover may be performed that transfers the current call to a secondfrequency, f₂, within the cell that has capacity for allocation of thesecond call. For illustrative purposes, assume a multi-line mobileterminal is engaged in a call on a carrier frequency, f₁, as depicted inFIG. 10B. In this instance, the multi-line mobile terminal is engaged ina call on time slot 1030 c, and all other time slots 1030 a-1030 b and1030 d-1030 h are currently in use for other calls (as illustrativelydesignated with cross hatches). In the present example, anotheravailable frequency, f₂, has multiple time slots 1031 a, 1031 c, and1031 f-1031 h available and thus may be selected for an intra-cellhandover of the multi-line mobile terminal call. In the depictedexample, a handover of the in-progress call is made from time slot 1030c of frequency f₁ to time slot 1031 a of frequency f₂ as depicted inFIG. 10C. A second time slot, e.g., time slot 1031 c, of the frequency,f₂, to which the mobile terminal has been transferred may then beallocated for the second call request (step 1020), and the incoming callmay then be set-up on frequency f₂ (step 1022). Thus, both calls arethen carried on frequency f₂. The set-up subroutine cycle may then endaccording to step 1024.

FIG. 11A is a flowchart 1016 that depicts processing of a secondaryintra-cell handover procedure that facilitates concurrent termination ofmultiple calls with a mobile terminal in accordance with an embodiment.The processing steps of FIG. 11A may be implemented ascomputer-executable instructions executable by a processing system, suchas a processing system of one or more of a mobile switching center orbase station subsystem. The processing steps of FIG. 11A generallycorrespond to step 1016 depicted in FIG. 9.

The secondary intra-cell handover procedure is invoked (step 1102),e.g., on a determination that the carrier frequency, f₁, of thein-progress call does not have any available time slots for a secondincoming call, and on identification of another carrier frequency, f₂,that has a single time slot available for a call. In the exampledepicted in FIG. 11B, the multi-line mobile terminal has an in-progresscall allocated on time slot 1130 c of the carrier frequency f₁, and allother time slots 1130 a-1130 b and 1130 d-1130 h are currently allocatedfor other calls (as illustratively designated with cross hatches). Thecarrier frequency f₂ has a single time slot 1131 a that is currentlyavailable. A call is selected on the carrier frequency, f₁, on which themulti-terminal call has an in-progress call (step 1104). In the presentexample, a call allocated on time slot 1130 a is selected for anintra-cell handover. Selection of a call on the frequency f₁ excludesselection of the in-progress multi-terminal mobile call for which asecond call request has been received and may exclude any othermulti-terminal call that is in-progress with two concurrent calls. Uponselection of a suitable call on the carrier frequency f₁, an intra-cellhandover may be performed for the selected call to transition theselected call from the carrier frequency f₁ to f₂ (step 1106). In thepresent example, the selected call is transferred from time slot 1130 aof frequency f₁ to time slot 1131 a of frequency f₂ as depicted in FIG.11C. Thus, the time slot 1130 a of carrier frequency f₁ on which thetransitioned call previously used is freed. Accordingly, the freed timeslot 1130 a on the carrier frequency f₁ may then be allocated for theincoming call request to the multi-line mobile terminal having anin-progress call on the carrier frequency f₁ (step 1108). The secondcall may then be set-up with the multi-line mobile terminal on the timeslot allocated on frequency f₁ (step 1110) as depicted in FIG. 11D. Thesecondary intra-cell handover procedure cycle may then end (step 1112).

In accordance with another embodiment, carrier frequency selection forincoming calls may be made with a preference to carrier frequencies thatdo not have a multi-line mobile terminal call allocated thereon. Thisimplementation may be made in an attempt to maintain time slotavailability on a carrier frequency that has a multi-line mobileterminal call allocated thereon such that, in the event a second callrequest is directed to the mobile terminal having an in-progress call,the second call may be allocated on the carrier frequency on which themobile terminal is already engaged in the first call.

FIG. 12 is a flowchart 1200 depicting call set-up processing routineproviding preference to carrier frequencies that do not have amulti-line mobile terminal call allocated thereon for call requestsimplemented in accordance with an embodiment. The call set-up processingdescribed with reference to FIG. 12 may be implemented as executableinstructions of a computer-readable medium for execution by a processingsystem, such as a mobile switching center, a base station controller, abase transceiver station, or other components of a base stationsub-system.

The call set-up processing routine is invoked (step 1202), and a callset-up request is received (step 1204). The call set-up request may beevaluated to determine if either an origination device or a destinationdevice of the call set-up request is a multi-line mobile terminal (step1206). In the event either of the origination or termination devicecomprises a multi-line mobile terminal, the call may be set-up with amulti-line terminal call set-up routine (step 1208), e.g., according tothe set-up routine described with reference to FIG. 7 or the call set-uproutine described with reference to FIG. 9. The call set-up routinecycle may then end (step 1222).

Returning again to step 1206, in the event that neither the originationor destination device of the call set-up request is a multi-line mobileterminal, a carrier frequency with an available time slot may beselected (step 1210) and evaluated to determine if any calls allocatedon the selected carrier frequency are terminated at a multi-line mobileterminal (step 1212). In the event that no call allocated on theselected carrier frequency is terminated with a multi-line mobileterminal, a time slot of the selected frequency may be allocated for thecall request (step 1214), and the call may then be set-up on theallocated time slot (step 1216). The call set-up routine cycle may thenend according to step 1222.

Returning again to step 1212, in the event the selected frequency has amulti-line mobile terminal call in progress allocated thereon, anevaluation may be made to determine if any other carrier frequencies ofthe serving cell have any available time slots for the call request(step 1218). If any other carrier frequencies have an available timeslot for the call request, processing may return to step 1210 to selectthe identified carrier frequency and thereafter evaluate the selectedfrequency to determine if any multi-line mobile terminal calls areallocated thereon. In the event that it is determined at step 1218 thatno other carrier frequencies have available time slots for the callrequest, a time slot of the selected frequency may be allocated for thecall request (step 1220), and the call may then be set-up on theallocated time slot according to step 1216. In this manner, preferenceis given to setting up calls that do not involve a multi-line mobileterminal on frequencies that do not have a multi-line mobile terminalcall allocated thereon. Thus, the likelihood of a time slot beingavailable for a second call to a multi-line mobile terminal engaged in acall is advantageously enhanced.

In other embodiments, one or more frequencies of a cell's frequency setmay be designated for carrying only calls of multi-line mobile terminalsto further enhance the likelihood of a time slot being available for amulti-line mobile terminal to receive a second call. An attempt to setup a call involving a multi-line mobile terminal is first made with thefrequencies allocated for multi-line mobile terminals, and if none areavailable, the call may be set up on the other frequencies allocated fornon multi-line mobile terminals. In a similar manner, when nonmulti-line mobile terminal calls are placed or received in a cell, asubset of the frequency set of the cell may be allocated for nonmulti-line mobile terminals, and an attempt to locate an availablechannel within the frequencies allocated for non multi-line mobileterminals is made. In the event that no channels of frequenciesallocated for non multi-line mobile terminals are available, the nonmulti-line mobile terminal call may then be set up on a frequencyallocated for multi-line mobile terminals.

In accordance with the multi-line termination embodiments describedabove, various mid-call services that are conventionally provided over asingle line may be extended for multiple lines. In this manner, mid-callservices may be managed by multi-line mobile terminal 140, e.g., by calltermination application 412. Processing of the first and second callsmay be performed by call termination application 412 on two distinct andfully allocated channels, e.g., either two physical channels such as themulti-line call scenario depicted and described with reference to FIG.6B, or on multiple channels allocated on a common carrier frequency.Thus, for example, if the user elected to hold the second call, calltermination application 412 receives any content on the second channeland discards or otherwise ignores the second channel content therebyprohibiting the second channel content from being processed for outputto the user, e.g., by disallowing decoded content of the second channelfrom being processed by analog baseband 308 for output over headsetspeaker 316.

In one implementation, a mobile-controlled call waiting service may beserviced by call termination application 412. Conventional call waitingservices are managed by the carrier network. However, in someembodiments disclosed herein, the carrier network(s) may be unaware ofthe multi-line capabilities of mobile terminal 140, and in otherembodiments advantages may be realized by provisioning of a call waitingservice at mobile terminal 140. Assume for illustrative purposes thatmobile terminal 140 has an in-progress call on a first line, and that asecond call request is received by mobile terminal 140 on the secondline, e.g., on a separate physical carrier received on a secondantenna/transceiver of the mobile terminal or, alternatively,multiplexed with the first call on a common frequency. In this instance,call termination application 412 may be adapted to recognize a secondincoming call, e.g., by a ringing signal or a ring message that directsthe mobile terminal to output a ring tone over loudspeaker 330, whilethe first call is in-progress. In response to detection of a ringingsignal or ring message, call termination application 412 may be adaptedto discard the ringing signal or ring message or otherwise prohibit aring tone from output over loudspeaker 330 and instead output a suitablesecond call alert, e.g., a “beep” on speaker 316. If the user selects tohold the call, call termination application 412 may output a call acceptnotification to the network supplying the second call to the mobileterminal. In this instance, the second call is connected to mobileterminal 140, and call termination application 412 holds the call at themobile terminal. That is, a channel is allocated and the second call isset-up between mobile terminal 140 and the carrier network of the secondcall. Any content received by mobile terminal 140, e.g., voice content,supplied by the second calling party may be discarded or otherwiseprohibited from output on headset speaker 316 while the second call ison hold. To this end, when the second call is set-up, call terminationapplication 412 may periodically provide an indication to the secondcalling party over the second call channel that the call is on hold.Other mid-call services may similarly be provisioned. A menu of userselectable options may be provided to the user, e.g., on display 328,that allows for selection of various mid-call options, such as holdcall, accept call, conference call, forward call, transfer call or thelike. Call termination application 412 may process the second callaccording to the user response.

In another embodiment, the second call may be conferenced with the firstin response to user selection of a conference call selection.Accordingly, call termination application 412 may output a call acceptnotification to the network supplying the second call notification tothe mobile terminal. In this instance, the second call is connected tomobile terminal 140, and call termination application 412 may bridgedecoded content of the second call with the first call. Additionally,call termination application 412 may be responsible for directing anyuplink content originated at mobile terminal 140 to both the first andsecond calls.

FIG. 13 is a flowchart depicting call termination application 412processing for providing mid-call services in accordance with anembodiment. The processing steps of FIG. 13 may be implemented ascomputer-executable instructions executable by a processing system, suchas a processing system of mobile terminal 140. The call terminationapplication is invoked (step 1302), and a call request is received atthe mobile terminal (step 1304). An evaluation may be made to determineif any call is currently in progress on the other line of the mobileterminal (step 1306). If no call is currently in progress, the incomingcall may be set-up through conventional routines (step 1308), and thecall termination application processing cycle may then end (step 1330).

Returning again to step 1306, in the event that another call isdetermined to be in progress on the other mobile terminal line, the calltermination application may remove the incoming ringing signal (or ringmessage) (step 1310) such that a ring tone is not output over the mobileterminal loudspeaker 330. A second incoming call notification, e.g., anaudible beep or other tone, may then be output through headset speaker316 along with a menu of user selectable call handling options ondisplay 328 (step 1312). An evaluation may then be made to determine ifthe user has selected a second call rejection option (step 1314). In theevent that the user has rejected the second incoming call, the carriernetwork may be notified of the call rejection (step 1316) such that anetwork managed call termination, e.g., with a voice mail server or thelike, may be provided to the second calling party.

Returning again to step 1314, if the user has not rejected the call, thecarrier network of the second call may be notified with a callacceptance, and the second call may be set-up on the second channel(step 1318). An evaluation may then be made to determine what callhandling procedure has been selected by the user, e.g., whether the userhas elected to put the second incoming call on hold (step 1320). If theuser has selected to put the second call on hold, the call terminationapplication may then proceed to a mobile-terminated call hold routine(step 1322). For example, the call termination application mayperiodically transmit a notification to the second calling party thatthe call is on hold while discarding or otherwise prohibitingloudspeaker output of any audio content received on the second channelby the mobile terminal. If the user has not selected a call holdservice, an evaluation may be made to determine if the user has selectedcall conferencing of the second call (step 1324). If it is determinedthat the user selected call conferencing, the call terminationapplication may proceed to invoke a mobile-terminated call conferencingsubroutine (step 1326). For example, the call termination applicationmay bridge any decoded audio content received on the second channel withdecoded audio content received on the first channel, and the bridgedcontent may be output on headset speaker 316 and transmitted on thefirst call uplink channel and the second call uplink channel. Othermobile-terminated mid-call services may likewise be invoked (step 1328).

In accordance with another embodiment, a call termination application412 may facilitate a call forwarding mid-call service for receiving acall on one channel, and forwarding the received call from the mobileterminal on another channel. For example, assume mobile terminal 140receives a call on a first channel associated with a first subscriptionallocated for the mobile terminal. Call termination application 412 maybe configured with a directory number for call-forwarding. When a callis received by mobile terminal 140, the mobile terminal may redirect thecall as a call originated from the mobile terminal on another channel inassociation with the second subscription. In this manner, the user mayavoid incurring network tariffs levied against the first account forcall forwarding charges, as the call is effectively redirected throughthe second account as an outbound call.

In another embodiment, the first call may be transferred to a anotherdestination using a second line on the multi-line mobile such that themulti-line mobile phone bridges the incoming call with the outgoing calland the user of the multi-line phone may remove themselves from theconversation. In this case the conversation will continue using themulti-line phone without the user participating in the call. During thesetup of the transfer, the user of the multi-line phone may firstconsult with the second destination before invoking the transfer (e.g.,Consultative Transfer), or may elect to transfer the call withoutconsultation (e.g., Blind Transfer).

FIG. 14 is a flowchart of a call transfer procedure executed at amulti-line mobile terminal in accordance with an embodiment. Theprocedure is invoked (step 1402) while a multi-line mobile terminal hasan in-progress call on a first line of the mobile terminal. A transfercommand is received by call termination application 412 (step 1404),e.g., selection of a transfer option by the user of the multi-linemobile terminal. A destination number for forwarding the call may thenbe received by call termination application 412 (step 1406). Thedestination number may be input by the user after selection of the callforward command, or may alternatively be pre-configured with calltermination application 412. An evaluation may be made to determine if aBlind transfer has been selected (step 1408). In the event that a blindtransfer was selected, call termination application 412 may connect tothe destination number on the second line and bridge the call of thefirst line to the second line (step 1410). Call termination application412 may suppress any audio input at the multi-line terminal so onlyaudio supplied on the first line is transferred on the uplink of thesecond line. Call termination application 412 may additionally suppressany audio received on the second line that is bridged to the uplink ofthe first line from being output by the mobile terminal. Thus, from auser perspective, the multi-line mobile terminal does not appear to beconnected with the transferred call. That is, a user of the mobileterminal may not actively participate in the forwarded call. Theprocedure cycle may then end (step 1420).

Returning again to step 1408, in the event that a Blind transfer was notselected thus indicating that a Consultative transfer is to beperformed, call termination application 412 may place the in-progresscall on hold (step 1412) by discarding or otherwise suppressing anyaudio received on the downlink of the first line and any audio inputreceived at the mobile terminal. Call termination application 412 mayalso periodically transmit a notification to the first line party thatthe call is on hold. The second line of the multi-line mobile terminalmay then be used to connect with the destination number (step 1414). Inthis instance, the user of the multi-line mobile terminal may engage ina conversation with the party at the destination number. During thistime, call termination application 412 may present a complete transferprompt, e.g., on display 328. On receipt of complete transfer command,the first line may be bridged with the second line (step 1418). To thisend, call termination application 412 may suppress any audio input atthe multi-line terminal so only audio supplied on the first line istransferred on the uplink of the second line. Call terminationapplication 412 may additionally suppress any audio received on thesecond line that is bridged to the uplink of the first line from beingoutput by the mobile terminal. Thus, from a user perspective, themulti-line mobile terminal does not appear to be connected with thetransferred call.

As described, mechanisms for allocating multiple subscriptions to asingle mobile terminal are provided. A mobile terminal adapted toterminate multiple concurrent calls is described. In one implementation,a network need not have any configuration data regarding the multi-linecapabilities of the mobile terminal. In other implementations,network-centric mechanisms are provided for allowing multiple concurrentcalls to be terminated by a mobile terminal. Multiple concurrent callsmay be terminated at a mobile terminal on separate carrier frequenciesor alternatively may be terminated on a common carrier frequency.Although the specific network architecture and nomenclature are depictedand described according to the GSM, it is understood that this is doneso for illustrative purposes only and that the network architecture onwhich embodiments disclosed herein may be applied is not limited to anyparticular standard, but rather may be equivalently implemented on anyother communications system supporting any variety of cellularcommunication systems, e.g., D-AMPS, GSM, CDMA, IS-41, ANSI-41, UMTS,etc. For example, variants of the disclosed embodiments may beimplemented in a CDMA system by, rather than allocating timeslots onparticular frequencies, instead allocating orthogonal codes (e.g., WalshCodes) on a common frequency.

The flowcharts of FIGS. 7-13 depict process serialization to facilitatean understanding of disclosed embodiments and are not necessarilyindicative of the serialization of the operations being performed. Invarious embodiments, the processing steps described in FIGS. 7-13 may beperformed in varying order, and one or more depicted steps may beperformed in parallel with other steps. Additionally, execution of someprocessing steps of FIGS. 7-13 may be excluded without departing fromembodiments disclosed herein.

The illustrative block diagrams and flowcharts depict process steps orblocks that may represent modules, segments, or portions of code thatinclude one or more executable instructions for implementing specificlogical functions or steps in the process. Although the particularexamples illustrate specific process steps or procedures, manyalternative implementations are possible and may be made by simpledesign choice. Some process steps may be executed in different orderfrom the specific description herein based on, for example,considerations of function, purpose, conformance to standard, legacystructure, user interface design, and the like.

Aspects of the present invention may be implemented in software,hardware, firmware, or a combination thereof. The various elements ofthe system, either individually or in combination, may be implemented asa computer program product tangibly embodied in a machine-readablestorage device for execution by a processing unit. Various steps ofembodiments of the invention may be performed by a computer processorexecuting a program tangibly embodied on a computer-readable medium toperform functions by operating on input and generating output. Thecomputer-readable medium may be, for example, a memory, a transportablemedium such as a compact disk, a floppy disk, or a diskette, such that acomputer program embodying the aspects of the present invention can beloaded onto a computer. The computer program is not limited to anyparticular embodiment, and may, for example, be implemented in anoperating system, application program, foreground or background process,driver, network stack, or any combination thereof, executing on a singlecomputer processor or multiple computer processors. Additionally,various steps of embodiments of the invention may provide one or moredata structures generated, produced, received, or otherwise implementedon a computer-readable medium, such as a memory.

Although embodiments of the present disclosure have been described indetail, those skilled in the art should understand that they may makevarious changes, substitutions and alterations herein without departingfrom the spirit and scope of the present disclosure.

What is claimed is:
 1. A method, comprising: determining a mobileterminal is currently terminated with an in-progress first call;determining the mobile terminal is available to accept a second call;determining the first carrier frequency has no time slots available forthe second call; identifying a second carrier frequency that has aplurality of available time slots; setting up the second call with themobile terminal while the first call is maintained in-progress, whereinthe second call is setup by allocating a time slot of the second carrierfrequency; and performing an intra-cell handover of the first call fromthe first carrier frequency to the second carrier frequency.
 2. Themethod of claim 1, comprising receiving a call request directed to themobile terminal.
 3. The method of claim 1, comprising identifying adifferent carrier frequency that has more time slots available than acarrier frequency allocated to the first call.
 4. The method of claim 3,wherein the time slot of the different carrier frequency is differentfrom the carrier frequency allocated to the first call.
 5. The method ofclaim 1, wherein the first call is allocated on a first carrierfrequency.
 6. The method of claim 1, wherein setting up the second callcomprises setting up the second call on the second carrier frequency. 7.A non-transitory computer-readable storage medium havingcomputer-executable instructions for execution by a processor, thecomputer-executable instructions, comprising: instructions thatdetermine a mobile terminal is currently terminated with an in-progressfirst call; instructions that determine the mobile terminal is availableto accept a second call; instructions that determine the first carrierfrequency has no time slots available for the second call; instructionsthat identify a second carrier frequency that has a plurality ofavailable time slots; instructions that set up the second call with themobile terminal while the first call is maintained in-progress, whereinthe second call is setup by allocating a time slot of the second carrierfrequency; and instructions that perform an intra-cell handover of thefirst call from the first carrier frequency to the second carrierfrequency.
 8. The non-transitory computer-readable storage medium ofclaim 7, comprising instructions that receive a call request directed tothe mobile terminal.
 9. The non-transitory computer-readable storagemedium of claim 7, comprising instructions that identify a differentcarrier frequency that has more time slots available than a carrierfrequency allocated to the first call.
 10. The non-transitorycomputer-readable storage medium of claim 9, wherein the time slot ofthe different carrier frequency is different from the carrier frequencyallocated to the first call.
 11. The non-transitory computer-readablestorage medium of claim 7, wherein the first call is allocated on afirst carrier frequency.
 12. The non-transitory computer-readablestorage medium of claim 7, wherein the instructions that set up thesecond call comprise instructions that set up the second call on thesecond carrier frequency.
 13. A system, comprising: a mobile terminal,comprising: a first antenna; a first transceiver coupled to the firstantenna; a second antenna; and a second transceiver coupled to thesecond antenna; a processing system that executes computer-executableinstructions that terminates calls with the mobile terminal, wherein themobile terminal is configured to concurrently receive a first call on afirst channel and a second call on a second channel; wherein the firstcall is received on a channel of a first carrier frequency over thefirst antenna and the first transceiver, and wherein the second call isreceived on a channel of a second carrier frequency over the secondantenna and the second transceiver; wherein the processing system:determines a mobile terminal is currently terminated with an in-progressfirst call; determines the mobile terminal is available to accept asecond call; determines the first carrier frequency has no time slotsavailable for the second call; identifies a second carrier frequencythat has a plurality of available time slots; sets up the second callwith the mobile terminal while the first call is maintained in-progress,wherein the second call is setup by allocating a time slot of the secondcarrier frequency; and performs an intra-cell handover of the first callfrom the first carrier frequency to the second carrier frequency. 14.The system of claim 13, further comprising: a first subscriber identitymodule associated with a first cellular service subscription; and asecond subscriber identity module associated with a second cellularservice subscription.
 15. The system of claim 13, wherein the processingsystem provides mid-call services for the second call and wherein themid-call services comprises a service selected from the group consistingof a call forwarding service, a call waiting service, and a callconferencing service.
 16. The system of claim 13, wherein the processingsystem detects a call request of the second call while the first callis-in progress, prohibits a ringing signal from being output by themobile terminal, and outputs an indication of a second call request. 17.The system of claim 13, wherein the processing system receives anindication that the second call is accepted and notifies a carriernetwork from which the second call is inbound to the mobile terminalthat the second call is accepted.
 18. The system of claim 13, wherein atleast one of: content of the first channel is bridged with content ofthe second channel; and audio content of the second call is bridged withaudio content of the first call and output at the mobile terminal. 19.The system of claim 13, further comprising a microphone for receivingaudio input at the mobile terminal, wherein the audio input istransmitted on an uplink of the first channel and an uplink of thesecond channel.
 20. The system of claim 13, wherein the second call isestablished with at least one of: a call forwarding destination numberin response to receipt of the first call, and wherein content of thefirst channel is bridged to the second channel; and a call transferdestination number in response to a user supply of a call transfercommand.